This invention relates generally to a rail system wherein the cars may be supported above, below or to either side of a track, and more particularly to such a system wherein stresses on the wheel flanges are substantially avoided during changes in horizontal loads acting on the car.
In U.S. Pat. Nos. 3,122,105 and 3,194,179 issued to Lester G. Scherer monorail systems are disclosed wherein track beams generally I-shaped in cross-section are used for support of the travelling cars having lower wheels sloping inwardly toward the car and upper wheels disposed horizontally. In both systems the lower wheels rotate about axes perpendicular to the resultant of forces exerted by the lower wheels on its rail. Also, the lower wheels of both systems lie in respective planes which are parallel to such resultant forces although such planes do not intersect at the center of gravity of the car. Instead, the planes in which the lower wheels lie in both monorail systems intersect with vertical planes containing the centers of gravity of both cars, such intersections being located upwardly of the centers of gravity themselves. Accordingly, the horizontal force changes acting on the rails as the car travels around curves and as a result of horizontal wind loads will create an unstable condition for the cars and possibly a derailment of the lower wheels. Therefore, in the monorail system shown in FIG. 8 of U.S. Pat. No. 3,122,105, the bottom wheels are quite likely to disengage from the concave lower rail with the car swinging outwardly of the track as the curve is negotiated thereby resulting in all of the load being applied vertically on the upper horizontal wheels so as to effect a dangerous condition and even collapse of the car. Also, the horizontal stresses in the monorail system of U.S. Pat. No. 3,194,179, while the car is negotiating a curve, must be resisted by flanges of the sloping lower wheels by a wedging action only. In such a prior art arrangement as well as in the standard railway car system, the horizontal forces occurring as the car moves along a curve in the track must be resisted by a single flange of one of the spaced apart wheels and by a single rail. Accordingly, the wheels must be sufficiently strong to resist the entire horizontal cornering loads in both directions respectively applied at single points on the outer rims. The axles of the standard railway car systems must therefore be likewise sufficiently strong in order to take up the vertical bending loads in one direction and take up the horizontal loads in another direction applied to the flange of the wheel. And, the tolerances required between the flanges of the wheels create a condition where even without any horizontal loads the cars exhibit a weaving behavior during travel.
Moreover, in the later Scherer patent of those mentioned, the upper wheels are mounted on the car through a pivot pin to compensate for changes and elevation of the car when loaded. The pivot axis is, however, located above the upper wheels so as quite possibly cause the upper wheels to swing upwardly about this pivot axis thereby causing collapse of the car. And, springs 144 are provided in this patent for adjusting the axis of rotation of the lower wheels so as to remain perpendicular to the resultant forces of the car directed toward the lower rail. The lower wheels nevertheless remain parallel to the resulting forces as in the manner discussed above.